The present invention relates to a switchgear, and more particularly, to a switchgear having an earth switch.
As the demand for electricity increases due to the development of industry, a power system is also becoming large capacity and super-high pressure, and according to this, stabilization and reliability of electric power facilities are very important.
Due to the surge in electricity demand, a high-Voltage Substation is in a tendency where a main circuit system thereof is sealed and concealed, and a control system thereof is rapidly changed to electronicization because of reasons such as a difficulty of securing a place to use, excessive maintenance cost, and ensuring stability, and is changing from an existing air or oil insulated substation to a gas insulated substation.
Generally, a switchgear is a device which is provided in a power transmission line or a power distribution line, performs opening/closing in a normal state, and stably protects a power system by opening a line in an abnormal state such as a ground fault and a short circuit.
The switchgear can be classified into an air-insulated switchgear (AIS), a solid-insulated switchgear (SIS), a gas-insulated switchgear (GIS), or the like according to an insulating medium.
The switchgear is an electrical device which is installed between a power supply side and a load side of the electric system, and protects a power system and a load device by safely cutting off the current when the circuit is opened or closed artificially in a normal current state or when an abnormal current such as a ground fault and a short circuit is generated.
Such a switchgear includes a bushing unit, a main bus, a gas circuit breaker, a disconnector switch, an earth switch, a current transformer, a moving unit, a control unit, and the like, which generally receive electricity from the high voltage power supply.
Here, the earth switch (ES) is a device which is installed at both ends of a circuit breaker, and serves to earth the main circuit manually during maintenance and inspection and to remove the current left in the conductors during maintenance or inspection of equipment.
FIG. 1 is a view illustrating a state where the earth switch of the switchgear according to the related art is disconnected, and FIG. 2 is a diagram illustrating a state where the earth switch of the switchgear according to the related art is connected.
As illustrated in FIGS. 1 and 2, the earth switch may be disposed inside a cabinet 1 of the switchgear of the related art. The earth switch may include a link 2 which is connected to an earth switch mechanism (not illustrated) and moves in the vertical direction, a horizontal connecting rod 4 which moves left and right according to the movement of the link 2, a vertical connecting rod 6 which move in the vertical direction according to the movement of the horizontal connecting rod 4, a mover 12 which rotates in accordance with the movement of the vertical connecting rod 6; a movable electrode 9 which rotates together with the mover 12; and a fixed electrode 8 which is connected to the movable electrode 9 and comes in contact with or is separated from the movable electrode 9.
The power of the link 2 can be transmitted to the horizontal connecting rod 4 by a first gear box 3 and the power of the horizontal connecting rod 4 can be transmitted to the vertical connecting rod 6 by a second gear box 5.
The movable electrode 9 can rotate together with the mover 12 about a rotation shaft 11 and can be come into contact with or separated from the fixed electrode 8 by the rotation motion thereof. The rotation shaft 11 may be provided in the supporter 10 and the supporter 10 may be provided with a guide hole 10A for guiding the rotation of the mover 12.
However, in a case of the switchgear of the related art, there is a problem that, in a case where a large current corresponding to the fault current is energized in a state where the fixed electrode 8 and the movable electrode 9 are in contact with each other, or the fixed electrode 8 and the movable electrode 9 which are connected to a system having a state of a living line are in contact with each other, some fusion may occur between the fixed electrode 8 and the movable electrode 9. A mechanism having a very large opening force is required to overcome the fusion and to separate the fixed electrode 8 and the movable electrode 9, which may lead to an increase in manufacturing cost and a shortening of the life of the earth switch.
The related technical literature of the present invention includes KR 20-2010-0011682 U (published Dec. 1, 2010) and KR 20-0437070 U (registered Oct. 25, 2007).